Contactless high-gloss solution

hotset has developed the Z-System with the objective of avoiding unsightly weld seams, mat surfaces and other quality defects on the surfaces of injection-molded components. Since its premiere two years ago, an increasing number of tool constructors and injection molders have shown interest in this innovative solution for the partial and cyclic temperature control of tools. The company has now extended its Z-System world with a process for the contactless and repetition-accurate temperature measurement in high-gloss polished cavities.

The cavities of many steel injection molding tools for the production of visually high-quality plastic parts for automotive construction, lighting technology and the consumer industry feature demarcated high-gloss areas. They represent the negative template for the realization of flawlessly smooth surfaces. Therefore, both tool constructors and injection molders wish to know exact details regarding the thermal characteristics at and on these high-gloss polished zones. However, this application case places extremely high demands on the measurement technology used, as the elaborately-polished surface must not be contacted, which is why tactile methods are excluded from the start; and the reflexions of the high-gloss surface cause optical methods of operation to fail. Even conventional temperature measurements with thermal cameras are pushed to their limits, as this determines an estimated value tendency at most, and is not reproducible. “This problem really concerned us, meaning that over the past few months we have been intensively engaged in the search for alternative processes. The results of our efforts are now matured”, says Andreas Filler, Project Manager at hotset. The thermodynamics experts in Lüdenscheid have managed to develop a completely innovative solution for temperature measurement on high-gloss polished cavities which impresses through a whole series of specific advantages: It not only works without contact, quickly, precisely and with high repetition accuracy, but also enables temperature measurements to be undertaken both at certain points and across areas. Therefore, the user can obtain comprehensive information regarding the thermodynamic occurrences at and on the tool surface.

Non-touch function using infrared

This new measurement process by hotset is part of the further development of the Z-System for the partial-cyclical temperature control of tools. It is based on the use of a compact infrared camera and the application of a special measurement process. The IR camera is so small that it can be positioned with a magnetic holder between the open tool halves, and can record the temperature directly at the cavity. The measurement process used not only enables us to measure the temperature statically at the high-gloss zones, but also depicts all progressions and changes in temperature – and this in real-time and graphically visualized in a color temperature-time diagram. Product Manager Andreas Filler explains: “With heating rates up to 60 Kelvin per second, the thermal occurrences on the high-gloss polished surfaces of the cavities are extremely dynamic and erratic. In order to obtain informative results here, a special measurement process is therefore required which can precisely and quickly record these extreme thermodynamics.” Thanks to our practical experience with the Z-System and based on our many decades of expertise gained in the field of thermodynamics, it was possible for the Engineering Team at hotset to drive the development of this new measurement process on quickly enough so that it will be available to users as a further innovative component of the Z-System world prior to the end of 2017. Andreas Filler emphasizes “that the new `high-gloss solution´ is particularly aligned for dynamic temperature control using the Z-System and its corresponding control technology”.

Impetus from automotive construction

The Z-System presented by hotset almost two years ago has been developed – amongst others in collaboration with the Kunststoff-Institut (Plastics Institute) in Lüdenscheid – with the objective of providing manufacturers of injection-molded plastic parts with a process-safe solution for the temperature control of tools which avoid process-related surface imperfections (weld seams, matt surfaces, jetting) and realizing particularly thin wall thicknesses. Both factors play a central role in the manufacture of design-oriented products, optical components and vehicle interiors. “In particular, it was the demand from many customers in the automotive industry for our Z-System which provided the impetus for us to develop a dynamic process for temperature measurement on the high-gloss surfaces of tool cavities”, says Andreas Filler.

Incidentally: The new measurement system by hotset can also be used for control measurements within the scope of Quality Assurance. In case of a tool change, it is therefore possible, for example, to store a measurement layout which has been defined once as a measurement point, and then to subsequently call this up again for comparison measurements.

The contactless, quick, precise and high repeat accuracy temperature measurement of the high-gloss polished areas on injection molding tools is facilitated through a new measurement process by hotset.